Blood Pressure Calculator
Check your blood pressure category.
Input
Result
What is a Blood Pressure Calculator?
A Blood Pressure Calculator classifies your systolic and diastolic readings into standard blood pressure categories (normal, elevated, stage 1 hypertension, stage 2 hypertension, or hypertensive crisis) and calculates your mean arterial pressure (MAP). It helps you quickly understand where your numbers fall on the clinical scale.
How to calculate blood pressure category and MAP manually (the formula)
MAP formula: MAP = diastolic BP + ⅓(systolic BP − diastolic BP).
Categories (ACC/AHA guidelines): Normal: systolic < 120 and diastolic < 80. Elevated: systolic 120–129 and diastolic < 80. Stage 1 hypertension: systolic 130–139 or diastolic 80–89. Stage 2 hypertension: systolic ≥ 140 or diastolic ≥ 90. Hypertensive crisis: systolic > 180 or diastolic > 120.
Example calculation
For a reading of 130/85 mmHg: MAP = 85 + ⅓(130 − 85) = 85 + ⅓(45) = 85 + 15 = 100 mmHg. The category is Stage 1 hypertension (systolic 130–139 or diastolic 80–89).
Common mistakes
- Confusing systolic and diastolic — Systolic is the top number and diastolic is the bottom. Swapping them produces a wrong category and MAP.
- Only checking one number — Both systolic and diastolic matter. A systolic of 125 with diastolic of 82 is still Stage 1 hypertension because the diastolic is ≥ 80.
- Taking a single reading as final — Blood pressure fluctuates throughout the day. A diagnosis should be based on multiple readings taken over time, not one measurement.
Frequently asked questions
What do the blood pressure numbers mean?
Systolic (top number) measures pressure when your heart beats. Diastolic (bottom number) measures pressure when your heart rests between beats.
What is a normal blood pressure reading?
A normal reading is below 120/80 mmHg. Elevated is 120–129 systolic with diastolic below 80. High blood pressure (hypertension) starts at 130/80.
What is mean arterial pressure (MAP)?
MAP is the average pressure in your arteries during one cardiac cycle. It is calculated as MAP = diastolic + 1/3(systolic − diastolic). A normal MAP is 70–100 mmHg.
Why is MAP important?
MAP represents the driving force that pushes blood through your circulatory system. It is critical for ensuring adequate perfusion to vital organs like the brain and kidneys.
Can I check my blood pressure at home?
Yes, home monitoring with a validated cuff is recommended. Sit quietly for 5 minutes, keep your feet flat, and rest your arm at heart level before taking a reading.
How often should I check my blood pressure?
If you have normal readings, once a year is sufficient. If you have elevated or high readings, your doctor may recommend daily or weekly monitoring.